中国主要牧区雪灾遥感监测评估模型研究

该文以中国雪灾高发区的西藏那曲地区为例，主要介绍了在试验区雪灾背景数据库支持下，利用ＮＯＡＡ／ＡＶＨＲＲ卫星遥感资料对雪灾进行判别，预测及对灾情损失进行综合评估的一些技术和方法，其内容包括：（１）用于雪灾危险等级分析与判定的判别模型；（２）用于灾情发展趋势模拟与预测的预测模型；（３）用于灾情损失综合评估与估算的评介模型。并运用这些模型对１９９５年２－３月发生在西藏那曲的雪灾进行实时分析，其结果和实     

冬季青藏高原地面辐射平衡

本文根据实测资料建立了冬季青藏高原上地面辐射平衡与日照百分率、地面反射率之间的经验公式,并用此公式试验了纬度、时间、地面反射率和日照百分率对地面辐射平衡的影响。试验结果表明:冬季高原地面辐射能收支的盈亏状况是由地理纬度和地面反射率决定的。天空遮蔽状况(本文用日照百分率表示)仅影响其盈亏值的大小。亦即地面辐射平衡的地理分布形式由地理纬度和地面反射率所决定,但正、负中心的数值还受天空遮蔽状况的影响。冬季青藏高原地面辐射平衡场是一个由地理因子(地理纬度和自然地理带)作用下形成的基本场叠加上一个地面积雪区形成的扰动场。长江和黄河源区的巴颜喀拉山和藏北草原是冬季高原地面加热场最可能出现异常的关键区。     

Estimation of spectral reflectance of snow from IRS-1D LISS-III sensor over the Himalayan terrain

The sensor onboard the satellite views the earth as a plain surface and consequently the satelliteobtained spectral radiances cannot represent true values over a mountainous terrain. The relative magnitudes of terrain slope and its aspect with respect to the sun's position will determine the amount of direct solar radiation incident on an undulating surface. Estimation of spectral reflectance from satellite data forms an important component in many of the snow and glacier studies. The spectral reflectance of snow is influenced by its various parameters. The changes in snowpack characteristics as a result of various metamorphic processes, with age, can cause variations in its spectral reflectances. Since, the terrain geometry also modifies the amount of reflected radiation from a rugged surface, one has to correct the estimated spectral reflectances for terrain topography so as to use them in deriving the snowpack characteristics accurately. Also, the amounts of melt runoff originating from glaciers having different slopes and orientations will not be the same. Considering these aspects, a model has been developed to estimate the terrain corrected spectral reflectances over the Himalayan terrain using the Linear Imaging Self Scanner-III data of the Indian Remote Sensing Satellite. The model computes spectral reflectances from satellitebased radiance measurements and includes the effect of the terrain topography on the incident solar radiation. The terrain slope and its aspect are generated from the digital elevation model of the region. The analysis carried out over the Beas Basin, Himachal Pradesh, India, indicated a variation of 22% in the amount of incident solar radiation for an increase of 10‡ in terrain slope. Further, the terrain with south-east aspect received maximum amount of solar radiation. The large differences observed between the uncorrected and terrain corrected reflectances in the shortwave infrared band (B5), which is not saturated over the snow covered region, suggest that the terrain slope and its aspect cannot be neglected in estimating the accurate spectral reflectances over the Himalayan terrain.     

地质环境合理开发利用集对论准则

资源与环境是当今社会面临的两大问题，是影响可持续发展的重要因素。地质环境具有资源与灾害的双重属性，不合理的开发利用将引发环境负效应，其影响具有扩散性与延滞性。本文借鉴集对论基本原理与方法，对城市化进程中地质环境的合理开发利用提出总体思路及其具体途径。     

Evaluation of the SNOWPACK model’s metamorphism and microstructure in Canada: a case study

The snow thermodynamic multi-layer model SNOWPACK was developed to address the risk of avalanches by simulating the vertical properties of snow. Risk and stability assessments are based on the simulation of the vertical variability of snow microstructure, as well as on snow cohesion parameters. Previous research has shown systematic error in grain size simulations (equivalent optical grain size) over several areas in northern Canada. To quantify the simulated errors in snow grain size and uncertainties in stability, the snow specific surface area (SSA) was measured with a laser-based instrument. Optical grain size was retrieved to validate the optical equivalent grain radius from SNOWPACK. The two study plots are located in Glacier National Park, BC, and Jasper National Park, AB, Canada. Profiles for density and stratigraphic analysis were obtained as well as grain size profiles, combined with snow micropenetrometer (SMP) measurements. Density analysis showed good agreement with the simulated values (R² = 0.76). Optical grain size analysis showed systematic overestimation of the modeled values, in agreement with the current literature. The error in SSA evolution for a rounding environment was mostly constant, whereas error for conditions driven by a temperature gradient was linked to the size of the facetted grains.     

陇南地质灾害降雨区划及临界雨量研究

陇南地质灾害主要分布在白龙江流域、白水江流域和西汉水流域,主要形式为泥石流、滑坡,其分布密度比云南东川、大盈江及四川西昌等都大。其产生的主要气象条件为降雨(雷阵雨、暴雨、连阴雨)。本文重点介绍陇南地质灾害的分布、陇南地质灾害降雨区划及临界雨量值的确定。     

论资源与环境的协调发展

本文概述了我国的资源现状,人类生活和生产引起的滑坡、崩塌、地裂缝、地面沉降、海水入侵、水土流失、洪涝灾害、水体污染等环境地质灾害,进而探讨了资源、环境与人口间的关系,提出了可持续发展的若干建议：提高对资源有限性的认识;树立保护环境、防止污染的意识;加强计划生育,控制人口增长;全民动员,美化生存环境。     

玉门地区铁路防沙体系建设的研究

论文分析了戈壁风沙流区铁路沙害现状,提出了玉门地区铁路防护体系建设中树种选择的依据,并筛选了二白杨、沙枣、花棒、柠条以及线叶柳等一些适合该区铁路防护林营造的树种。研究结果还表明,在该地区的铁路沙害防治中,工程措施和生物措施相结合是一种行之有效的治理措施,"客土造林"和乔、灌、草相结合是提高铁路防护林效益的关键。该研究结果为今后该地区的沙漠化整治和铁路防沙体系的建设提供了一定的依据。     

Modelling Chorabari Lake outburst flood,Kedarnath, India

In this study, the Glacier Lake Outburst Flood(GLOF) that occurred over Kedarnath in June 2013 was modeled using integrated observations from the field and Remote Sensing(RS). The lake breach parameters such as area, depth, breach, and height have been estimated from the field observations and Remote Sensing(RS) data. A number of modelling approaches, including Snow Melt Runoff Model(SRM), Modified Single Flow model(MSF), Watershed Management System(WMS), Simplified Dam Breach Model(SMPDBK) and BREACH were used to model the GLOF. Estimations from SRM produced a runoff of about 22.7 m3 during 16–17, June 2013 over Chorabari Lake. Bathymetry data reported that the lake got filled to its maximum capacity(3822.7 m3) due to excess discharge. Hydrograph obtained from the BREACH model revealed a peak discharge of about 1699 m3/s during an intense water flow episode that lasted for 10–15 minutes on 17 th June 2013. Excess discharge from heavy rainfall and snowmelt into the lake increased its hydrostatic pressure and the lake breached cataclysmically.     

Reflectance variation in boreal landscape during the snow melting period using airborne imaging spectroscopy

We aim a better understanding of the effect of spring-time snow melt on the remotely sensed scene reflectance by using an extensive amount of optical spectral data obtained from an airborne hyperspectral campaign in Northern Finland. We investigate the behaviour of thin snow reflectance for different land cover types, such as open areas, boreal forests and treeless fells. Our results not only confirm the generally known fact that the reflectance of a melting thin snow layer is considerably lower than that of a thick snow layer, but we also present analyses of the reflectance variation over different land covers and in boreal forests as a function of canopy coverage. According to common knowledge, the highly variating reflectance spectra of partially transparent, most likely also contaminated thin snow pack weakens the performance of snow detection algorithms, in particular in the mapping of Fractional Snow Cover (FSC) during the end of the melting period. The obtained results directly support further development of the SCAmod algorithm for FSC retrieval, and can be likewise applied to develop other algorithms for optical satellite data (e.g. spectral unmixing methods), and to perform accuracy assessments for snow detection algorithms.A useful part of this work is the investigation of the competence of Normalized Difference Snow Index (NDSI) in snow detection in late spring, since it is widely used in snow mapping. We conclude, based on the spectral data analysis, that the NDSI -based snow mapping is more accurate in open areas than in forests. However, at the very end of the snow melting period the behavior of the NDSI becomes more unstable and unpredictable in non-forests with shallow snow, increasing the inaccuracy also in non-forested areas. For instance in peatbogs covered by melting snow layer (snow depth < 30 cm) the mean NDSI -0.6 was observed, having coefficient of variation as high as 70%, whereas for deeper snow packs the mean NDSI shows positive values.